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???
11/03/06 17:33
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 		 #127334 - I'm not so sure about that one ...
Responding to: ???'s previous message
Jan Waclawek said:
"We always wanted to kick off the drivers which cause unnecessary delays in our legacy 8255-based board..."

JW


I agree that the external buffers that the 8255 needed in order to do useful work were a pain in the hindquarters, the delay wasn't the reason. I frequently had to deal with the drivers on Intel's boards, and they were frequently the wrong type. They were output drivers when I needed inputs ... they were inverters when I needed buffers ... they were unregistered when I needed registers ... AND, of course, they were always on the wrong connector pins.

The 15 ns they added to the propagation delay in or out didn't generally affect anything.

RE





List of 61 messages in thread
TopicAuthorDate
Any value to a fast 8255?            01/01/70 00:00      
   Fast 8255            01/01/70 00:00      
      8255 breakeven volume            01/01/70 00:00      
         there are a few things ...            01/01/70 00:00      
            8255 vs 6824            01/01/70 00:00      
               too many users failed            01/01/70 00:00      
            Reconfiguration            01/01/70 00:00      
               Yes, one had to know how the device behaved.            01/01/70 00:00      
               the 8255 was tough to learn, but in its crummy way            01/01/70 00:00      
   peaple would rather forget the 8255            01/01/70 00:00      
      Why do you suppose that is, Jez?            01/01/70 00:00      
   raison d'etre            01/01/70 00:00      
      Main reason, I think            01/01/70 00:00      
         There are other reasons, too.            01/01/70 00:00      
            Thanks for sharing your experience!            01/01/70 00:00      
      There's also a large replacement part market.            01/01/70 00:00      
         but for that you have to compste with Intersil            01/01/70 00:00      
            Intersil still only offers the \'80\'s technology            01/01/70 00:00      
               May be I am wrong, but...            01/01/70 00:00      
                  It hasn't got the same sort of ports as the 805x            01/01/70 00:00      
                     Yes, you are right            01/01/70 00:00      
                     8255            01/01/70 00:00      
                        Why would a novice build a PCB?            01/01/70 00:00      
                           Products and packages            01/01/70 00:00      
                              gee ... and I've never before heard of Tekmos ...            01/01/70 00:00      
   quick thoughts            01/01/70 00:00      
      You're on the right track, EXCEPT ...            01/01/70 00:00      
   on analogy...            01/01/70 00:00      
   8255 in India            01/01/70 00:00      
      It makes little sense to teach 8085, or does it?            01/01/70 00:00      
         I Agree            01/01/70 00:00      
            Do not attend            01/01/70 00:00      
               Every Collage            01/01/70 00:00      
               Not "College Think"            01/01/70 00:00      
      just had a thought - Lynn, Jez            01/01/70 00:00      
         Enhanced 8255            01/01/70 00:00      
            If all one could get is PLCC ...            01/01/70 00:00      
         well i have come up with a way.            01/01/70 00:00      
            There is a problem with FPGA\'s ...            01/01/70 00:00      
               nRD is needed in the 8255 as a clock            01/01/70 00:00      
                  Perhaps that\'s because they use latches            01/01/70 00:00      
                     on using undefined states            01/01/70 00:00      
                        grounding chip select is risky            01/01/70 00:00      
                           but what if it is grounded?            01/01/70 00:00      
               clinging to the past            01/01/70 00:00      
                  Don't forget the Maxim/Dallas parts, they use 5V0            01/01/70 00:00      
                     as usual apples and oranges            01/01/70 00:00      
                        you need to see it from Richard's viewpoint            01/01/70 00:00      
                           he has the right to his viewpoint ...            01/01/70 00:00      
                              There's room for disagreement on that ...            01/01/70 00:00      
                        "development" and "replacement" are different            01/01/70 00:00      
                           well, for the (in)famous "universal board"            01/01/70 00:00      
                              If there's a market, it would be for THE part            01/01/70 00:00      
                                 again mixing parametres            01/01/70 00:00      
                                    the value of an improved 8255 in legacy applicatio            01/01/70 00:00      
                                       I'm not so sure about that one ...            01/01/70 00:00      
                                          OK that was just one - bad - example...            01/01/70 00:00      
                                             My point and point of view, all along has been ...            01/01/70 00:00      
                                    let's clear up some misconceptions ...            01/01/70 00:00      
      8085?            01/01/70 00:00      
         RE:8085?            01/01/70 00:00      

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